Often it is desirable to modify a mass produced LED light source or LED lighting device, such as an LED module array to be used in a custom application requiring colored lighting. LED module arrays are modular LED systems that are used as light sources for many applications, such as backlighting signs, lighting coves, reveals, stairways, showcases, shelving systems, decorations, and others. Flexibility and scalability of modular array systems make them easy to implement in a variety of lighting environments, if the color of the light output of the system can be properly adapted.
Typically, such modules are offered in several shades of white that follow black body curves (signified by Kelvin temperature values) and occasionally in limited colors, such as red, green, blue, amber, and yellow. When a specific color is desired that is not among the limited color offerings typically manufactured, custom production processes are used, which require large minimum orders well beyond the needs of most custom projects (in the tens of thousands of units). It is therefore prohibitively expensive to produce custom colors for all but the largest of custom projects. Further, it is generally impossible to receive samples of colors to be produced, since LED packages cannot necessarily be produced in small quantities that would match the results of mass production, and even when they can, there is no guarantee that the color will appear identical when mass produced.
An alternative option is to use RGB LED lighting sources, capable of being programmed to output a variety of colors. These systems combine programmed intensities of red, green, and blue, to enable the production of a wide variety of colors. However, these units are expensive to produce, require control systems (an additional expense) and often burn out faster than dedicated colors (particularly for brighter colors that run hotter). Therefore, producing different shades of colors in LEDs is typically difficult and expensive to install, set up, maintain, and service. Further, the color of programmable installations tends to change over time, causing problems when a specific custom color is required in a long term installation.
Further, several types of applications require very precise colors. As discussed above, if the precise colors required are atypical, they may not be available—particularly for smaller projects. If the precise colors are available, manufacturing with the required tolerances may require special tooling and production runs, and may therefore be prohibitively expensive.
For example, custom color projects often require LED signage that appears in the same color (and shade) when viewed during the daytime or at night. These projects often involve a corporate color that may be proprietary or trademarked (such as a college or sport team color). Therefore, precision in the color is required, and the color is unlikely to be available off the shelf. For daytime viewing, a color filter is typically applied to a front surface of signage, which can provide an accurate color. However, in these installations, when a traditional LED lighting device is placed within the signage, the color generally appears washed out. This is particularly problematic in the case of lighter colors, such as pink, teal, orange, magenta, yellow, and others.
Further, some custom signage is designed to provide a color during the daytime but to illuminate in white at night. One example of such application uses a DuLite proprietary acrylic panel. The panel is colored to the desired color for daytime viewing, and only appears as white at night when an LED light having a specified precise color temperature is used.
Production of the specialized white shade with the tolerances required for this type of custom application often requires a large order with a high cost per LED. Further, because the white temperature required may not be useful in other applications, it is very expensive to keep stock of the required LED light sources, since such expensive and precisely manufactured LEDs may have no other commercial demand.
Because of the high cost and bulk requirements of the required precisely manufactured LEDs, RGB LEDs may be used to produce the required color temperature. However, RGB LEDs are imprecise when used for white colors, and tend to shift over time—particularly for shades of white.
Previously developed systems for changing the output color of an LED array are flawed for these applications. For example, theater lighting applications, such as those used for incandescent and fluorescent applications, typically used color filters designed to be swapped in front of a housing. However, such assemblies do not work well when used with LED stage lighting, and do not transition well to LED lighting arrays or linear bars for permanent installations using existing filters. The filters filter too much light, making the LED devices on which they were applied too dim for use. Further, the existing systems could not be matched to custom applications as required, nor are they configured for integration into durable housings for LEDs for long term outdoor use.
Some manufacturers develop LED solutions with pigmented plastic covers or housings. However, the pigmented cover must them be mass produced, and cannot be modified—leading to similar stocking and manufacturing issues to those described above.
There is a need, therefore, for a LED lighting device that can be inexpensively produced and installed in custom colors tailored to the installation.